No, dreamweaver accepts it fine.
I can use:
http://localhost/mysites/mysitecom/default.asp
but not
http://localhost/mysites/mysite.com/default.asp
I get:
The page cannot be displayed
There is a problem with a program on the page you are trying to reach, and the page cannot be displayed.
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Please try the following:
Open the localhost home page, and then look for links to the information you want.
Click the Refresh button, or try again later.
HTTP 403.1 Forbidden: Execute Access Forbidden
Internet Information Services
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Technical Information (for support personnel)
Background:
You have attempted to execute a CGI, ISAPI, or other executable program from a directory that does not allow programs to be executed.
More information:
Microsoft Support